Method and apparatus for designing force sensations in force feedback computer applications

ABSTRACT

A design interface tool for designing force sensations for use with a host computer and force feedback interface device. A force feedback device is connected to a host computer that displays the interface tool. Input from a user is received in the interface to select a type of force sensation to be commanded by a host computer and output by a force feedback interface device. Input, such as parameters, is then received from the user which designs and defines physical characteristics of the selected force sensation. A graphical representation of the characterized force sensation is displayed on the host computer which provides a visual demonstration of a feel of the characterized force sensation so that the user can view an effect of parameters on said force sensation. The characterized force sensation is output to a user manipulatable object of the force feedback device so that the user can feel the designed force sensation, where the graphical representation is updated in conjunction with the output of the force sensation. The user can iteratively modify force sensation characteristics and feel the results, and store the characterized force sensations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/782,878, filed Feb. 23, 2004 which is a continuation of U.S. patentapplication Ser. No. 09/734,630, filed Dec. 11, 2000, on behalf of LouisB. Rosenberg et al., entitled “Designing Force Sensations For ForceFeedback Computer Applications,” now U.S. Pat. No. 6,697,086, which is acontinuation-in-part of parent patent application Ser. No. 08/566,282,filed Dec. 1, 1995, on behalf of Louis B. Rosenberg et al., entitled,“Method and Apparatus for Controlling Force Feedback Interface SystemsUtilizing a Host Computer,” now U.S. Pat. No. 5,734,373 and Ser. No.08/846,011, filed Apr. 25, 1997, on behalf of Rosenberg et al.,entitled, “Method and Apparatus for Designing and Controlling ForceSensations in Force Feedback Computer Applications,” now U.S. Pat. No.6,147,674 each of which assigned to the assignee of this presentapplication, and each of which are incorporated by reference herein intheir entirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to interface devices forallowing humans to interface with computer systems, and moreparticularly to computer interface devices that allow the user toprovide input to computer systems and allow computer systems to provideforce feedback to the user.

Users interact with computer systems for a variety of reasons. Acomputer system typically displays a visual environment to a user on adisplay output device. Using an interface device, a user can interactwith the displayed environment to perform functions and tasks on thecomputer, such as playing a game, experiencing a simulation or virtualreality environment, using a computer aided design system, operating agraphical user interface (GUI), or otherwise influencing events orimages depicted on the screen. Common human-computer interface devicesused for such interaction include a joystick, mouse, trackball, stylus,tablet, pressure-sensitive ball, or the like, that is connected to thecomputer system controlling the displayed environment. Typically, thecomputer updates the environment in response to the user's manipulationof a user-manipulatable physical object such as a joystick handle ormouse, and provides visual and audio feedback to the user utilizing thedisplay screen and audio speakers. The computer senses the userísmanipulation of the user object through sensors provided on theinterface device that send locative signals to the computer. Forexample, the computer displays a cursor, controlled vehicle, or othergraphical object in a graphical environment, where the location ormotion of the graphical object is responsive to the to the motion of theuser object. The user can thus control the graphical object by movingthe user object.

In some interface devices, tactile and/or haptic feedback is alsoprovided to the user, more generally known as “force feedback”. Thesetypes of interface devices can provide physical sensations which arefelt by the user manipulating a user manipulable object of the interfacedevice. For example, the Force-FX joystick controller from CH Products,Inc. and immersion Corporation may be connected to a computer andprovides forces to a user of the controller. Other systems might use aforce feedback mouse controller. One or more motors or other actuatorsare coupled to the joystick or other user object and are connected tothe controlling computer system. The computer system controls forces onthe joystick in conjunction and coordinated with displayed events andinteractions by sending control signals or commands to the actuators.The computer system can thus convey physical force sensations to theuser in conjunction with other supplied feedback as the user is graspingor contacting the joystick or other object of the interface device. Forexample, when the user moves the manipulatable object and causes adisplayed cursor to interact with a different displayed graphicalobject, the computer can issue a command that causes the actuator tooutput a force on the user object, conveying a feel sensation to theuser.

A problem with the prior art development of force feedback sensations insoftware is that the programmer of force feedback applications does nothave an intuitive sense as to how forces will feel when adjusted incertain ways, and thus must go to great effort to developcharacteristics of forces that are desired for a specific application.For example, a programmer may wish to create a specific spring anddamping force sensation between two graphical objects, where the forcesensation has a particular stiffness, play, offset, etc. In currentforce feedback systems, the programmer must determine the parameters andcharacteristics of the desired force by a brute force method, by simplysetting parameters, testing the force, and adjusting the parameters inan iterative fashion. This method is cumbersome because it is often notintuitive how a parameter will affect the feel of a force as it isactually output on the user object; the programmer often may not even beclose to the desired force sensation with initial parameter settings.Other types of forces may not be intuitive at all, such as a springhaving a negative stiffness, and thus force sensation designers may havea difficult time integrating these types of sensations into softwareapplications. Thus, a tool is needed for assisting the programmer ordeveloper in intuitively and easily setting force feedbackcharacteristics to provide desired force sensations.

SUMMARY OF THE INVENTION

The present invention is directed to designing force sensations outputby a force feedback interface device. A controlling host computerprovides a design interface tool that allows intuitive and simple designof a variety of force sensations.

More particularly, a design interface for designing force sensations foruse with a force feedback interface device is described. The forcesensation design interface is displayed on a display device of a hostcomputer. Input from a user is received in the interface, where theinput selects a type of force sensation to be commanded by a hostcomputer and output by a force feedback interface device. Input, such asparameters, is then received from a user which designs and definesphysical characteristics of the selected force sensation. A graphicalrepresentation of the characterized force sensation is displayed on adisplay device of the host computer. The graphical representationprovides the user with a visual demonstration of a feel of thecharacterized force sensation such that said user can view an effect ofparameters on said force sensation. The characterized force sensation isoutput to a user manipulatable object of the force feedback interfacedevice such that the user can feel the designed force sensation. Thegraphical representation is updated in conjunction with the forcesensation being output on the user object, promoting furtherunderstanding of the effects of the characterization on the output forcesensation. The user can preferably input additional changes to thecharacterized forces sensation after experiencing the feel of thesensation and feel the changed force sensation. Thus, in an iterativeprocess, the user can design effective force sensations through actualexperience of those sensations. The user can preferably store thecharacterization or parameters of the designed force sensation to astorage medium that can be accessed by other programs on the hostcomputer or other computers. Other programs that control force feedbackcan thus utilize the designed force sensation in applications such asgames, simulations, or graphical interfaces.

A wide variety of types of force sensations can be designed in theinterface tool of the present invention. Described types includeconditions, effects, and dynamics. Some force sensations include asimple mode of graphical representation that is more intuitive butoffers less control over parameters that an advanced mode. In theadvanced mode, a force versus user object motion profile is displayed,where the user may adjust parameters of the selected force sensation bydragging displayed control points of the profile. Represented forcesensations include a damping condition, a spring condition, a slopecondition, a texture condition, and periodic waves. The user can alsodesign compound force sensations including multiple single forcesensations. For example, a preferred graphical representation of a slopecondition includes a hill image and a ball image, where the user movesthe ball with the user object. The force on the ball provided by anegative spring stiffness is intuitively analogized by the visualrepresentation of the ball rolling down the hill and feeling theappropriate forces. In one embodiment, the force feedback interfacedevice includes a microprocessor separate from the host computer system.The microprocessor receives commands from the host computer system,reads sensors of the interface device and reports positions of said userobject to the host computer, and commands actuators of the interfacedevice to output the force sensation on the user object.

The present invention advantageously provides a simple, easy-to-usedesign interface tool for designing force feedback sensations. Given thelarge variety of possible force sensations and the often unexpectedresults when modifying the several parameters of force sensations, thedesign interface tool of the present invention meets the needs of forcesensation designers that wish to create force sensations as close totheir needs as possible. The graphical design interface of the presentinvention allows a force sensation programmer or developer to easily andintuitively design force sensations, conveniently experience thedesigned force sensations, and visually understand the effect of changesto different aspects of the force sensations.

These and other advantages of the present invention will become apparentto those skilled in the art upon a reading of the followingspecification of the invention and a study of the several figures of thedrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for controlling a force feedbackinterface device of the present invention;

FIGS. 2 a-b are top plan and side elevational views, respectively, of afirst embodiment of a mechanism for interfacing a user manipulatableobject with the force feedback device of FIG. 1;

FIG. 3 is a perspective view of a second embodiment of a mechanism forinterfacing a user manipulatable object with the force feedback deviceof FIG. 1;

FIG. 4 is a block diagram illustrating a preferred functionality of theforce feedback system of FIG. 1;

FIG. 5 is a diagram of a displayed interface of the present inventionfor designing force sensations;

FIG. 6 is a diagram of the interface of FIG. 5 in which a design windowfor a spring condition is displayed;

FIGS. 7 a-c are diagrams of displayed graphical representations of aspring condition;

FIG. 8 is a diagram of a displayed graphical representation of a texturecondition;

FIGS. 9 a and 9 b are displayed graphical representations of a wallcondition;

FIG. 10 is a diagram of the interface of FIG. 5 in which a design windowfor a periodic effect is displayed;

FIG. 11 is a diagram of the interface of FIG. 5 in which a design windowfor a periodic sweep effect is displayed;

FIGS. 12-13 are diagrams of the interface of FIG. 5 in which a simplemode design window for a damping condition is displayed;

FIGS. 14-15 are diagrams of the interface of FIG. 5 in which an advancedmode design window for a damping condition is displayed;

FIGS. 16-17 are diagrams of the interface of FIG. 5 in which a simplemode design window for a spring condition is displayed;

FIGS. 18-19 are diagrams of the interface of FIG. 5 in which an advancedmode design window for a spring condition is displayed;

FIG. 20 is a diagram of the interface of FIG. 5 in which design windowsfor a compound force sensation are displayed;

FIGS. 21-23 are diagrams of the interface of FIG. 5 in which a designwindow for a slope condition is displayed;

FIG. 24 is a diagram of the interface of FIG. 5 in which a design windowfor a texture condition is displayed;

FIG. 25 is a diagram of the interface of FIG. 5 in which a design windowfor an angle spring condition is displayed; and

FIG. 26 is a diagram of the interface of FIG. 5 in which a design windowfor a periodic wave is displayed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a block diagram illustrating a force feedback interface system10 of the present invention controlled by a host computer system.Interface system 10 includes a host computer system 12 and an interfacedevice 14.

Host computer system 12 is preferably a personal computer, such as anIBM-compatible or Macintosh personal computer, or a workstation, such asa SUN or Silicon Graphics workstation. For example, the host computersystem can a personal computer which operates under the MS-DOS orWindows operating systems in conformance with an IBM PC AT standard.Alternatively, host computer system 12 can be one of a variety of homevideo game systems commonly connected to a television set, such assystems available from Nintendo, Sega, or Sony. In other embodiments,home computer system 12 can be a television “set top box” or a “networkcomputer” which can be used, for example, to provide interactivecomputer functions to users over networks.

In the described embodiment, host computer system 12 implements a hostapplication program with which a user 22 is interacting via peripheralsand interface device 14. For example, the host application program canbe a video game, medical simulation, scientific analysis program,operating system, graphical user interface, or other application programthat utilizes force feedback. Typically, the host application providesimages to be displayed on a display output device, as described below,and/or other feedback, such as auditory signals.

Host computer system 12 preferably includes a host microprocessor 16,random access memory (RAM) 17, read-only memory (ROM) 19, input/output(I/O) electronics 21, a clock 18, a display screen 20, and an audiooutput device 21. Host microprocessor 16 can include a variety ofavailable microprocessors from Intel, AMD, Motorola, or othermanufacturers. Microprocessor 16 can be single microprocessor chip, orcan include multiple primary and/or co-processors. Microprocessorpreferably retrieves and stores instructions and other necessary datafrom RAM 17 and ROM 19, as is well known to those skilled in the art. Inthe described embodiment, host computer system 12 can receive locativedata or a sensor signal via a bus 24 from sensors of interface device 14and other information. Microprocessor 16 can receive data from bus 24using I/O electronics 21, and can use I/O electronics to control otherperipheral devices. Host computer system 12 can also output a “forcecommand” to interface device 14 via bus 24 to cause force feedback forthe interface device.

Clock 18 is a standard clock crystal or equivalent component used byhost computer system 12 to provide timing to electrical signals used bymicroprocessor 16 and other components of the computer system. Clock 18is accessed by host computer system 12 in the force feedback controlprocess, as described subsequently.

Display screen 20 is coupled to host microprocessor 16 by suitabledisplay drivers and can be used to display images generated by hostcomputer system 12 or other computer systems. Display screen 20 can be astandard display screen, CRT, flat-panel display, 3-D goggles, or anyother visual interface. In a described embodiment, display screen 20displays images of a simulation or game environment. In otherembodiments, other images can be displayed. For example, imagesdescribing a point of view from a first-person perspective can bedisplayed, as in a virtual reality simulation or game. Or, imagesdescribing a third-person perspective of objects, backgrounds, etc. canbe displayed. A user 22 of the host computer 12 and interface device 14can receive visual feedback by viewing display screen 20.

Herein, computer 12 may be referred as displaying computer or graphical“objects” or “entities”. These computer objects are not physicalobjects, but is a logical software unit collections of data and/orprocedures that may be displayed as images by computer 12 on displayscreen 20, as is well known to those skilled in the art. For example, acursor or a third-person view of a car might be consideredplayer-controlled computer objects that can be moved across the screen.A displayed, simulated cockpit of an aircraft might also be consideredan “object”, or the simulated aircraft can be considered acomputer-implemented “entity”.

Audio output device 21, such as speakers, is preferably coupled to hostmicroprocessor 16 via amplifiers, filters, and other circuitry wellknown to those skilled in the art and provides sound output to user 22from the host computer 18. Other types of peripherals can also becoupled to host processor 16, such as storage devices (hard disk drive,CD ROM drive, floppy disk drive, etc.), printers, and other input andoutput devices.

An interface device 14 is coupled to host computer system 12 by abi-directional bus 24. The bi-directional bus sends signals in eitherdirection between host computer system 12 and the interface device.Herein, the term “bus” is intended to generically refer to an interfacesuch as between host computer 12 and microprocessor 26 which typicallyincludes one or more connecting wires, wireless connection, or otherconnections and that can be implemented in a variety of ways. In thepreferred embodiment, bus 24 is a serial interface bus providing dataaccording to a serial communication protocol. An interface port of hostcomputer system 12, such as an RS232 or Universal Serial Bus (USB)serial interface port, connects bus 24 to host computer system 12. Otherstandard serial communication protocols can also be used in the serialinterface and bus 24, such as RS-422, MIDI, or other protocols wellknown to those skilled in the art. The USB can also source power todrive peripheral devices and may also provide timing data that isencoded along with differential data.

Alternatively, a parallel port of host computer system 12 can be coupledto a parallel bus 24 and communicate with interface device using aparallel protocol, such as SCSI or PC Parallel Printer Bus. Also, bus 24can be connected directly to a data bus of host computer system 12using, for example, a plug-in card and slot or other access of computer12. Bus 24 can be implemented within a network such as the Internet orLAN; or, bus 24 can be a channel such as the air, etc. for wirelesscommunication. In another embodiment, an additional bus 25 can beincluded to communicate between host computer system 12 and interfacedevice 14. For example, bus 24 can be coupled to the standard serialport of host computer 12, while an additional bus 25 can be coupled to asecond port of the host computer system, such as a “game port”. The twobuses 24 and 25 can be used simultaneously to provide a increased databandwidth.

Interface device 14 includes a local microprocessor 26, sensors 28,actuators 30, a user object 34, optional sensor interface 36, anoptional actuator interface 38, and other optional input devices 39.Interface device 14 may also include additional electronic componentsfor communicating via standard protocols on bus 24. In the preferredembodiment, multiple interface devices 14 can be coupled to a singlehost computer system 12 through bus 24 (or multiple buses 24) so thatmultiple users can simultaneously interface with the host applicationprogram (in a multi-player game or simulation, for example). Inaddition, multiple players can interact in the host application programwith multiple interface devices 14 using networked host computers 12, asis well known to those skilled in the art.

Local microprocessor 26 is coupled to bus 24 and is preferably includedwithin the housing of interface device 14 to allow quick communicationwith other components of the interface device. Processor 26 isconsidered local to interface device 14, where “local” herein refers toprocessor 26 being a separate microprocessor from any processors in hostcomputer system 12. “Local” also preferably refers to processor 26 beingdedicated to force feedback and sensor I/O of interface device 14, andbeing closely coupled to sensors 28 and actuators 30, such as within thehousing for interface device or in a housing coupled closely tointerface device 14. Microprocessor 26 can be provided with softwareinstructions to wait for commands or requests from computer host 16,decode the command or request, and handle/control input and outputsignals according to the command or request. In addition, processor 26preferably operates independently of host computer 16 by reading sensorsignals and calculating appropriate forces from those sensor signals,time signals, and stored or relayed instructions selected in accordancewith a host command. Suitable microprocessors for use as localmicroprocessor 26 include the MC68HC711E9 by Motorola, the PIC16C74 byMicrochip, and the 82930AX by Intel Corp., for example. Microprocessor26 can include one microprocessor chip, or multiple processors and/orco-processor chips. In other embodiments, microprocessor 26 can includedigital signal processor (DSP) capability.

Microprocessor 26 can receive signals from sensors 28 and providesignals to actuators 30 of the interface device 14 in accordance withinstructions provided by host computer 12 over bus 24. For example, in apreferred local control embodiment, host computer system 12 provideshigh level supervisory commands to microprocessor 26 over bus 24, andmicroprocessor 26 manages low level force control loops to sensors andactuators in accordance with the high level commands and independentlyof the host computer 18. This operation is described in greater detailwith respect to FIG. 4. Microprocessor 26 can also receive commands fromany other input devices 39 included on interface apparatus 14 andprovides appropriate signals to host computer 12 to indicate that theinput information has been received and any information included in theinput information.

Local memory 27, such as RAM and/or ROM, is preferably coupled tomicroprocessor 26 in interface device 14 to store instructions formicroprocessor 26 and store temporary and other data. In addition, alocal clock 29 can be coupled to the microprocessor 26 to provide timingdata, similar to system clock 18 of host computer 12; the timing datamight be required, for example, to compute forces output by actuators 30(e.g., forces dependent on calculated velocities or other time dependentfactors). Timing data for microprocessor 26 can be alternativelyretrieved from a USB signal on bus 24.

In the preferred embodiment, sensors 28, actuators 30, andmicroprocessor 26, and other related electronic components are includedin a housing for interface device 14, to which user object 34 isdirectly or indirectly coupled. Alternatively, microprocessor 26 and/orother electronic components of interface device 14 can be provided in aseparate housing from user object 34, sensors 28, and actuators 30.Also, additional mechanical structures may be included in interfacedevice 14 to provide object 34 with desired degrees of freedom.Embodiments of mechanisms are described with reference to FIGS. 2 a-band 3.

Sensors 28 sense the position, motion, and/or other characteristics of auser object 34 of the interface device 14 along one or more degrees offreedom and provide signals to microprocessor 26 including informationrepresentative of those characteristics. Typically, a sensor 28 isprovided for each degree of freedom along which object 34 can be moved.Alternatively, a single compound sensor can be used to sense position ormovement in multiple degrees of freedom. An example of sensors suitablefor several embodiments described herein are digital optical encoders,which sense the change in position of an object about a rotational axisand provide digital signals indicative of the change in position. Asuitable optical encoder is the “Softpot” from U.S. Digital ofVancouver, Wash. Linear optical encoders, potentiometers, opticalsensors, velocity sensors, acceleration sensors, strain gauge, or othertypes of sensors can also be used, and either relative or absolutesensors can be provided.

Sensors 28 provide an electrical signal to an optional sensor interface36, which can be used to convert sensor signals to signals that can beinterpreted by the microprocessor 26 and/or host computer system 12.Digital optical encoders, for example, can be used. If analog sensors 28are used, an analog to digital converter (ADC) can convert the analogsignal to a digital signal that is received and interpreted bymicroprocessor 26 and/or host computer system 12. In alternateembodiments, sensor signals from sensors 28 can be provided directly tohost computer system 12 as shown by bus 24 i, bypassing microprocessor26.

Actuators 30 transmit forces to user object 34 of the interface device14 in one or more directions along one or more degrees of freedom inresponse to signals received from microprocessor 26. Typically, anactuator 30 is provided for each degree of freedom along which forcesare desired to be transmitted. Actuators 30 can include two types:active actuators and passive actuators. Active actuators include linearcurrent control motors, stepper motors, pneumatic/hydraulic activeactuators, a torquer (motor with limited angular range), a voice coilactuators, and other types of actuators that transmit a force to move anobject. For example, active actuators can drive a rotational shaft aboutan axis in a rotary degree of freedom, or drive a linear shaft along alinear degree of freedom. Passive actuators can also be used foractuators 30. Magnetic particle brakes, friction brakes, orpneumatic/hydraulic passive actuators can be used in addition to orinstead of a motor to generate a damping resistance or friction in adegree of motion.

Actuator interface 38 can be optionally connected between actuators 30and microprocessor 26. Interface 38 converts signals from microprocessor26 into signals appropriate to drive actuators 30. Interface 38 caninclude power amplifiers, switches, digital to analog controllers(DACs), analog to digital controllers (ADCís), and other components, asis well known to those skilled in the art. In alternate embodiments,interface 38 circuitry can be provided within microprocessor 26, inactuators 30, or in host computer 12.

Other input devices 39 can optionally be included in interface device 14and send input signals to microprocessor 26 or to host processor 16.Such input devices can include buttons, dials, switches, levers, orother mechanisms. For example, in embodiments where user object 34 is ajoystick, other input devices can include one or more buttons provided,for example, on the joystick handle or base and used to supplement theinput from the user to a game or simulation. The operation of such inputdevices is well known to those skilled in the art.

Power supply 40 can optionally be coupled to actuator interface 38and/or actuators 30 to provide electrical power. Power supply 40 can beincluded within the housing of interface device 14, or be provided as aseparate component. Alternatively, interface device 14 can draw powerfrom the USB (if used) and thus have no (or reduced) need for powersupply 40. Also, power from the USB can be stored and regulated byinterface device 14 and thus used when needed to drive actuators 30. Forexample, power can be stored over time in a capacitor or battery andthen immediately dissipated to provide a jolt force to the user object34.

Safety switch 41 is optionally included in interface device 14 toprovide a mechanism to allow a user to deactivate actuators 30, orrequire a user to activate actuators 30, for safety reasons. In thepreferred embodiment, the user must continually activate or close safetyswitch 41 during operation of interface device 14 to enable theactuators 30. If, at any time, the safety switch is deactivated(opened), power from power supply 40 is cut to actuators 30 (or theactuators are otherwise disabled) as long as the safety switch isopened. For example, one embodiment of safety switch is an opticalswitch located on user object 34 or on a convenient surface of a housingof interface device 14. The switch is closed when the user covers theoptical switch with a hand or finger, so that the actuators 30 willfunction as long as the user covers the switch. Safety switch 41 canalso provide a signal directly to host computer 12. Other types ofsafety switches 41 can be provided in other embodiments, such as anelectrostatic contact switch, a button or trigger, a hand weight safetyswitch, etc. If the safety switch 41 is not provided, actuator interface38 can be directly coupled to actuators 30.

User manipulable object 34 (“user object”) is a physical object, deviceor article that may be grasped or otherwise contacted or controlled by auser and which is coupled to interface device 14. By “grasp”, it ismeant that users may releasably engage a grip portion of the object insome fashion, such as by hand, with their fingertips, or even orally inthe case of handicapped persons. The user 22 can manipulate and move theobject along provided degrees of freedom to interface with the hostapplication program the user is viewing on display screen 20. Object 34can be a joystick, mouse, trackball, stylus (e.g. at the end of alinkage), steering wheel, sphere, medical instrument (laparoscope,catheter, etc.), pool cue (e.g. moving the cue through actuatedrollers), hand grip, knob, button, or other article.

FIG. 2 a is a top plan view and FIG. 2 b is a side elevational view ofone embodiment of an interface apparatus including a mechanicalapparatus 70 and user object 34, in which electromagnetic voice coilactuators are used to provide forces to the user object. Such voice coilactuators are described in greater detail in co-pending patentapplication Ser. No. 08/560,091 now U.S. Pat. No. 5,805,140,incorporated by reference herein. Interface apparatus 70 provides twolinear degrees of freedom to user object 34 so that the user cantranslate object 12 in a planar workspace along the X axis, along the Yaxis, or along both axes (diagonal movement). This embodiment is thuspreferred for use with a mouse, puck, or similar user object 34.

Apparatus 70 includes user object 34 and a board 72 that includes voicecoil actuators 74 a and 74 b and guides 80. Object 34 is rigidly coupledto board 72, which, for example, can be a circuit board etched withconductive materials. Board 72 is positioned in a plane substantiallyparallel to the X-Y plane and floats. Board 72 and object 34 may thus betranslated along axis X and/or axis Y, shown by arrows 78 a and 78 b andguided by guides 80, thus providing the object 34 with linear degrees offreedom. Board 72 is provided in a substantially right-angle orientationhaving one extended portion 82 a at 90 degrees from the other extendedportion 82 b.

Voice coil actuators 74 a and 74 b are positioned on board 72 such thatone actuator 74 a is provided on portion 82 a and the other actuator 74b is provided on portion 82 b. Wire coil 84 a of actuator 74 a iscoupled to portion 82 a of board 72 and includes at least two loopsetched onto board 72, preferably as a printed circuit board trace.Terminals 86 a are coupled to actuator drivers, so that host computer 12or microprocessor 26 can control the direction and/or magnitude of thecurrent in wire coil 84 a. Voice coil actuator 74 a also includes amagnet assembly 88 a, which preferably includes four magnets 90 and isgrounded, where coil 84 a is positioned between opposing polarities ofthe magnet.

The magnetic fields from magnets 90 interact with a magnetic fieldproduced from wire coil 84 a when current is flowed in coil 84 a toproduce forces. As an electric current I is flowed through the coil 84 avia electrical connections 86 a, a magnetic field is generated from thecurrent and configuration of coil 84 a. The magnetic field from the coilthen interacts with the magnetic fields generated by magnets 90 toproduce a force along axis Y. The magnitude or strength of the force isdependent on the magnitude of the current that is applied to the coil,the number of loops in the coil, and the magnetic field strength of themagnets. The direction of the force depends on the direction of thecurrent in the coil. A voice coil actuator can be provided for eachdegree of freedom of the mechanical apparatus to which force is desiredto be applied.

Limits 91 or physical stops can be positioned at the edges of the board72 to provide a movement limit. Voice coil actuator 74 b operatessimilarly to actuator 74 a. In yet other embodiments, the translatorymotion of board 72 along axes X and Y can be converted to two rotarydegrees of freedom, or additional degrees of freedom can be similarlyprovided with voice-coil actuation, such as an up-down or spin degreesof freedom or spin along/about a z-axis.

Voice coil actuator 74 a can also be used as a sensor to sense thevelocity, position, and or acceleration of board 72 along axis Y. Motionof coil 84 a along axis Y within the magnetic field of magnets 90induces a voltage across the coil 84 a, and this voltage can be sensed.This voltage is proportional to the velocity of the coil and board 72along axis Y. From this derived velocity, acceleration or position ofthe board 72 can be derived. In other embodiments, separate digitalsensors may be used to sense the position, motion, etc. of object 34 inlow cost interface devices. For example, a lateral effect photo diodesensor 92 can be used, including a rectangular detector 94 positioned ina plane parallel to the X-Y plane onto which a beam of energy 96 isemitted from a grounded emitter 98. The position of the board 72 andobject 34 can be determined by the location of the beam 96 on thedetector.

FIG. 3 is a perspective view of another embodiment of a mechanicalapparatus 100 suitable for providing mechanical input and output to hostcomputer system 12. Apparatus 100 is more appropriate for a joystick orsimilar user object 34. Apparatus 100 includes gimbal mechanism 140,sensors 28 and actuators 30. User object 34 is shown in this embodimentas a joystick having a grip portion 162.

Gimbal mechanism 140 provides two rotary degrees of freedom to object34. A gimbal device as shown in FIG. 3 is described in greater detail inco-pending patent application Ser. Nos. 08/374,288 and 08/400,233 nowU.S. Pat. Nos. 5,731,804 and 5,767,839, both hereby incorporated byreference in their entirety. Gimbal mechanism 140 provides support forapparatus 160 on grounded surface 142, such as a table top or similarsurface. Gimbal mechanism 140 is a five-member linkage that includes aground member 144, extension members 146 a and 146 b, and centralmembers 148 a and 148 b. Gimbal mechanism 140 also includes capstandrive mechanisms 164.

Ground member 144 includes a base member 166 and vertical supportmembers 168. Base member 166 is coupled to grounded surface 142. Avertical support member 168 is coupled to each of these outer surfacesof base member 166 such that vertical members 168 are in substantially90-degree relation with each other. Ground member 144 is coupled to abase or surface which provides stability for mechanism 140. The membersof gimbal mechanism 140 are rotatably coupled to one another through theuse of bearings or pivots. Extension member 146 a is rigidly coupled toa capstan drum 170 and is rotated about axis A as capstan drum 170 isrotated. Likewise, extension member 146 b is rigidly coupled to theother capstan drum 170 and can be rotated about axis B. Central drivemember 148 a is rotatably coupled to extension member 146 a and canrotate about floating axis D, and central link member 148 b is rotatablycoupled to an end of extension member 146 b at a center point P and canrotate about floating axis E. Central drive member 148 a and centrallink member 148 b are rotatably coupled to each other at the center ofrotation of the gimbal mechanism, which is the point of intersection Pof axes A and B. Bearing 172 connects the two central members 148 a and148 b together at the intersection point P.

Gimbal mechanism 140 is formed as a five member closed chain such thateach end of one member is coupled to the end of a another member. Gimbalmechanism 140 provides two degrees of freedom to an object 34 positionedat or near to the center point P of rotation, where object 34 can berotated about axis A and/or B. In alternate embodiments, object 34 canalso be rotated or translated in other degrees of freedom, such as alinear degree of freedom along axis C or a rotary “spin” degree offreedom about axis C, and these additional degrees of freedom can besensed and/or actuated. In addition, a capstan drive mechanism 164 canbe coupled to each vertical member 168 to provide mechanical advantagewithout introducing friction and backlash to the system. Sensors 28 andactuators 30 can be coupled to gimbal mechanism 140 at the link pointsbetween members of the apparatus, and can be combined in the samehousing of a grounded transducer 174 a or 174 b. A rotational shaft ofactuator and sensor can be coupled to a pulley of capstan drivemechanism 164 to transmit input and output along the associated degreeof freedom. User object 34 is shown as a joystick having a grip portion162 for the user to grasp. A user can move the joystick about axes A andB.

Other embodiments of interface apparatuses and transducers can also beused in interface device 14 to provide mechanical input/output for userobject 34. For example, interface apparatuses which provide one or morelinear degrees of freedom to user object 34 can be used.

FIG. 4 is a block diagram illustrating the preferred functionality ofthe force feedback system 10 of FIG. 1. The force feedback systemprovides a host control loop of information and a local control loop ofinformation in a distributed control system.

In the host control loop of information, force commands 180 are providedfrom the host computer to the microprocessor 26 and reported data 182 isprovided from the microprocessor 26 to the host computer. In onedirection of the host control loop, force commands 180 are output fromthe host computer to microprocessor 26 and instruct the microprocessorto output a force having specified characteristics. For example, in U.S.Pat. No. 5,734,373, a command protocol is disclosed in which a hostcommand includes a command identifier, specifying the type of force, andone or more command parameters, specifying the characteristics of thattype of force. The microprocessor decodes or parses the commandsaccording to local software or firmware. The host computer can alsoprovide other types of host commands to the microprocessor 26 tocharacterize reading data with sensors and reporting data.

In the other direction of the host control loop, the localmicroprocessor 26 receives the host commands 180 and reports data 182 tothe host computer. This data 182 preferably includes locative data (orsensor data) that describes the position of the user object 34 in one ormore provided degrees of freedom. In some embodiments, other locativedata can also be reported to the host computer, including velocityand/or acceleration data of the user object 34 and data describing thestates of buttons 39 and/or the states/positions of other input devices39 and safety switch 41. The host computer uses the data 182 to updateprograms executed by the host computer, such as a graphical simulationor environment, video game, graphical user interface, etc.

In the local control loop of information, actuator signals 184 areprovided from the microprocessor 26 to actuators 30 and sensor signals186 are provided from the sensors 28 and other input devices 39 to themicroprocessor 26. The actuator signals 184 are provided from themicroprocessor 26 to the actuators 30 to command the actuators to outputa force or force sensation. The microprocessor can follow local programinstructions (a “force routine”) as described in greater detail in U.S.Pat. No. 5,734,373, incorporated by reference herein. Herein, the term“force sensation” refers to either a single force or a sequence offorces output by the actuators 30 which provide a sensation to the user.For example, vibrations, textures, attractive forces, a single jolt, ora force “groove” are all considered force sensations, as are the dynamicsensations disclosed herein.

In the other direction of the local control loop, the sensors 28 (andother input devices/safety switch) provide sensor signals 186 to themicroprocessor 26 indicating a position (or other information) of theuser object in degrees of freedom. The microprocessor may use the sensorsignals in the local determination of forces to be output on the userobject, as well as reporting locative data in data 182 derived from thesensor signals to the host computer that represents the position (orother characteristics) of the user object 34, as explained above. Thedata 182 reported to the host computer by the microprocessor 26typically includes a direct representation of the position (or motion)of the user manipulatable object 34. The host computer updates anapplication program according to the newly-received position.

In a different, host-controlled embodiment that utilizes microprocessor26, host computer 12 can provide low-level force commands over bus 24,which microprocessor 26 directly transmits to the actuators. In yetanother alternate embodiment, no local microprocessor 26 is included ininterface system 10, and host computer 12 directly controls andprocesses all signals to and from the interface device 14, e.g. the hostcomputer directly controls the forces output by actuators 30 anddirectly receives sensor signals 186 from sensors 28 and input devices39.

Force Feedback Sensations

Because force feedback devices can produce such a wide variety of feelsensations, each with its own unique parameters, constraints, andimplementation issues, the overall spectrum of force sensations has beendivided herein into subsets. Herein, three classes of feel sensationsare discussed: spatial conditions (“conditions”), temporal effects(“effects” or “waves”), and dynamic sensations (“dynamics”). Conditionsare force sensations that are a function of user motion, effects areforce sensations that are a predefined profile played back over time,and dynamics are force sensations that are based on an interactivedynamic model of motion and time. These three types of force sensationsare described in greater detail in parent application Ser. No.08/846,011.

Conditions describe the basic physical properties of an interface devicebased on spatial motion of the interface. For example, a joystick devicehas basic properties such as the stiffness, damping, inertia, andfriction in the joystick handle. These elementary conditions define theunderlying feel of handle motion during general manipulation. Conditionscan also be barriers or obstructions (“walls”) that restrict spatialmanipulation of the stick, and can also be textures. Conditions are verycompelling physical sensations because they generate forces as afunction of the spatial motion of the interface device as caused by theuser. In most applications, conditions are used to tune the general feelof the device based upon provided parameters. For example, when flyingan F-16 fighter in a game, a joystick handle might be made to feel verystiff and heavy. When flying an old Spitfire, a joystick handle might bemade to feel loose and light. When the craft is damaged by an enemyfire, the joystick handle might be made to feel sticky with a scratchytexture.

Conditions are typically not associated with discrete sudden eventsduring game play or application use, but are rather backgroundconditions or background physical properties of application events,hence the name “conditions”. A condition is usually an environmentalfeel that is set up and experienced over an extended period. Conditionsmay create force sensations that are a function of user object position,user velocity, and/or user object acceleration. Preferred standard typesof conditions are springs, dampers, inertia, friction, texture, andwalls. A spring force is a restoring force that feels like stretching orcompressing a spring. A damper force is a drag resistance that feelslike moving through a viscous liquid. An inertia force sensation feelsas if the user is moving a heavy mass. A friction force sensation is acontact or rubbing resistance that encumbers free motion. A texture is aspatially varying resistance that feels like dragging a stick over agrating. A wall is an obstruction having a specified location that feelslike a hard stop or a soft cushion.

Commanding conditions of the above types involves specifying thecondition type and defining the unique physical properties associatedwith that type. Parameters can customize the feel of the force sensationby adjusting the location of the spring origin by assigning which axisor axes the spring is applied to, by limiting the maximum force outputof the spring sensation, etc. Another parameter is a trigger parameter,which defines when to create the condition sensation. In the simplestcase, the condition might be created (triggered) directly upon the callof the host command. In the more advanced case, the condition sensationbeing defined might be generated (triggered) upon a local event such asthe press of a button. By defining these parameters, a wide variety offeels can be created. By combining multiple springs, even more diversesensations can be defined. By combining one type of condition with otherconditions such as textures and friction, the diversity grows further.

Effects are force sensations that are closely correlated with discretetemporal events during game play. For example, a shuttlecraft is blastedby an alien laser, the user feels a physical blast that is synchronizedwith graphics and sound that also represent the event. The jolt willlikely have a predefined duration and possible have other parametersthat describe the physical feel of the event. While discrete, effectscan have a substantial duration n for example, if a small motor boat iscaught in the wake of a huge tanker, the bobbing sensation may be aneffect that lasts over an extended period and may vary over time.Effects are best thought of as predefined functions of time such asvibrations and jolts that can be “overlaid” on top of the backgroundconditions described above as foreground sensations. In other words,effects are forces that are defined and “played back” over time whencalled.

Effects fall into two classes as described herein: a) Force Signals andb) Force Profiles. A Force Signal is an effect that is defined based ona mathematical relationship between force and time. This mathematicalrelationship is defined using waveform conventions. For example, a ForceSignal might be defined as a force that varies with time based on asine-wave of a given frequency and magnitude to create a vibrationsensation. A Force Profile is an Effect that is defined based on astream of digitized data. This is simply a list of force samples thatare stored and played back over time. Using Force Signals, a complexsensation can be defined based on simple parameters such as Sine-Wave,50 Hz, 50% magnitude. An advantage of Force Profiles is that they allowfor more general shapes of forces, but require a significant amount ofdata to be transferred to and stored at the interface device 14. Aconvenient way of defining force effects is by common wave parameterssuch as source, magnitude, period, duration, offset, and phase. Once awaveform is defined, its shape can be adjusted using an envelope whoseshape is defined by further parameters such as Impulse Level and SettleTime, Fade Level and Fade Time. Further parameters can specify directionin vector space, degrees of freedom, and triggers (buttons).Furthermore, a single complex effect can be specified as a sequentialcombination of multiple simpler effects.

Three basic types of effects are periodic, constant force (vectorforce), and ramp. The periodic type of effect is the basic effectdescribed above, in which a signal source such as a sine wave, trianglewave, square wave, etc., has a frequency and amplitude and may be shapedfor a specific application. A vibration is the most common type ofperiodic force. A constant force is simply a constant magnitude outputover time, but also may be shaped using the envelope parametersdiscussed above to achieve a waveform that is shaped like the envelope.A ramp is simply a rising force magnitude followed by a falling forcemagnitude, and can be defined as a single half cycle of a triangle waveor other waveform. Other types, such as periodic sweep, vector force,pop, and smart pop, can also be defined, as disclosed in parentapplication Ser. No. 08/846,011.

Dynamic force sensations provide interactive force sensations based onreal-time dynamic simulations of physical systems. Dynamic sensationsinvolve real-time physical interactions based on 1) user motion as wellas 2) a physical system wherein user motion during the interactionaffects the behavior of the physical system. For example, if the userwades through swamp-muck in a violent manner that stirs up undulationsin the fluid, the userís rash motions will increase the difficulty oftravel because the undulations in the fluid will worsen as the userstruggles. But, if the user wades through the swamp-muck in a dexterousmanner that absorbs the undulations in the fluid, the user will have aneasier time passing through the muck. This example, like allinteractions with physical systems, demonstrates that how the userinfluences the system during the event will effect how the event feels.

High level dynamic sensation commands allow the host computer tocoordinate the feel and execution of the dynamic sensations with gamingor other application program interactions. Each dynamic sensation setsup a physical sensation within the local processing routine of theinterface device. Parameters defined by the programmer can tune thedynamic sensation for specific application events. Basic types ofdynamic sensations include Dynamic Control Law, Dynamic Recoil, DynamicImpact, Dynamic Liquid. Dynamic Inertia, Dynamic Center Drift, DynamicSling and Dynamic Paddle. Preferably, each of these sensations is basedon a basic physical system defined in Dynamic Control Law including adynamic mass that is connected to the user object 34 by a simulatedspring and a simulated damper. When the user object 34 moves, thesimulated mass moves because the spring and the damper link the twosystems “physically.” Depending upon how the mass, the spring, and thedamper parameters are defined, the mass might jiggle, jerk, orsluggishly lag behind the user object. Also, there are initialconditions that can be defined to help tune the feel sensation, and anambient damping parameter that defines the simulated medium that themass is moving in. The user feels the effects of the physical system andmay influence the physical system dynamically. These parameters can bevaried to provide the variety of dynamic sensations.

FIG. 5 illustrates a display device 20 displaying an interactivegraphical toolset interface 300 of the present invention that enablesdevelopers and programmers of force feedback (“users” of the interface)to design and implement force sensations rapidly and efficiently. Thegraphical environment allows conditions, effects (“waves”), and dynamicsto be defined through intuitive graphical metaphors that convey thephysical meaning of each parameter involved. As the parameters aremanipulated, sensations can be felt in real-time, allowing for aniterative design process that fine-tunes the feel to the designer'sexact need. Once the appropriate sensation is achieved, the interfacecan save the parameters as a resource and automatically generateoptimized code in a desired format that can be used directly within anapplication program. Thus, interface 300 handles most of the forcefeedback development process from force sensation design to coding. Withthese tools, force feedback programming becomes a fast and simpleprocess.

The challenge of programming for force feedback is not the act ofcoding. Force models to provide force sensations are available, and,once the desired force sensation is known and characterized, it isstraightforward to implement the force sensation using softwareinstructions. However, the act of designing force sensations to providea desired feel that appropriately match gaming or other applicationevents is not so straightforward. Designing force sensations and aparticular feel requires a creative and interactive process whereparameters are defined, their effect experienced, and the parameters aremodified until the sensations are at the desired characterization. Forexample, when designing conditions, this interactive process mightinvolve setting the stiffness of springs, sizing the deadband,manipulating the offset, and tuning the saturation values. Whendesigning effects, this might involve selecting a wave source (sine,square, triangle, etc.), setting the magnitude, frequency, and durationof the signal, and then tuning the envelope parameters. For a dynamicsensation, this might involve setting the dynamic mass, and then tuningresonance and decay parameters. With so many parameters to choose from,each applicable to a different type of force sensation, there needs tobe a fast, simple, and interactive means for sensation design. To solvethis need, the graphical interface 300 of the present invention allows auser to rapidly set physical parameters and feel sensations, after whichthe interface automatically generates the appropriate code for use in ahost computer application program.

Interface 300 enables interactive real-time sensation design ofconditions, effects, and dynamics, where parameters can be defined andexperienced through a rapid iterative process. Thus, it is preferredthat a force feedback interface device 14 be connected to the computerimplementing interface 300 and be operative to output commanded forcesensations. Intuitive graphical metaphors that enhance a programmer'sunderstanding of the physical parameters related to each sensation typeare provided in interface 300, thereby speeding the iterative designprocess. File-management tools are also preferably provided in interface300 so that designed force sensations can be saved, copied, modified,and combined, thereby allowing a user to establish a library of forcesensations. Once sensations are defined, the interface 300 preferablystores the parameters as “resources” which can be used by an applicationprogram. For example, by linking a force sensation resource into anapplication program, the resources can be converted into optimizedDirect-X code for use in an application in the Windows environment.Other code formats or languages can be provided in other embodiments.Interface 300 can be implemented by program instructions or code storedon a computer readable medium, where the computer readable medium can beeither a portable or immobile item and may be semiconductor or othermemory of the executing computer (such as computer 12), magnetic harddisk or tape, portable disk, optical media such as CD-ROM, PCMCIA card,or other medium.

As shown in FIG. 5, the interface 300 has three primary work areas: thesensation pallet 302, the button trigger pallet 304, and the designspace 306. Force sensations are created in the design space 306 and canbe saved and loaded into that space using standard file handlingfeatures.

To create a new force sensation, a sensation type is chosen from thesensation pallet 302. Pallet 302 is shown in an expandable tree format.The root of the tree includes the three classes 310 of force feedbacksensations described herein, conditions, waves (effects), and dynamics.Preferably, users can also define their own headings; for example, a“Favorites” group can be added, where force sensations with desirablepreviously-designed parameters are stored.

In interface 300, the conditions, waves, and dynamics classes are shownin expanded view. These classes may also be “compressed” so as to onlydisplay the class heading, if desired. When a class is displayed inexpanded view, the interface 300 displays a listing of all the sensationtypes that are supported by the hardware connected to the host computer12 for that class. For example, when programming for more recent orexpensive hardware supporting a large number of force sensation types, alist including many or all available sensation types is displayed. Whenprogramming for older or less expensive interface device hardware thatmay not implement all the sensations, some sensation types can beomitted or unavailable to be selected in the expanded view. Preferably,interface 300 can determine exactly what force sensations are supportedby a given interface device 14 connected to the host computer by usingan effect enumeration process, i.e., the host computer can requestinformation from the interface device, such as a version number, date ofmanufacture, list of implemented features, etc.

Once a sensation type is chosen from the sensation pallet 302, thesensation type is added to the design space 306. For example, in FIG. 5,an icon 308 for the selected force sensation “Damper” is displayedwithin the design space 306 window. Icon 308 can now be selected/openedby the user in order to set the parameters for the given sensation typeusing graphical development tools (described below). Multiple icons cansimilarly be dragged to the design space to create a more complex forcesensation. Once the parameters are specified for the given sensation,the sensation can be saved as a resource file. Using this process, auser can create a diverse library of feel sensations as resource files.Also, predefined libraries of sample resources from third party sourcesmight also be available.

Options displayed in the trigger button pallet 304 can also be selectedby the user. Trigger pallet 304 is used for testing force sensationsthat are going to be defined as button reflexes. For example, a forcesensation might be designed as a combination of a square wave and a sinewave that triggers when Button #2 of the interface device is pressed.The square wave would be created by choosing the periodic type 312 fromthe sensation pallet 302 and defining parameters appropriate for thesquare wave. A sine wave would then be created by choosing anotherperiodic type 312 from the sensation pallet 302 and defining theparameters appropriate for the sine wave. At this point, two periodicicons 308 would be displayed in the design space window 306. To test thetrigger, the user can just drag and drop these icons 308 into the Button2 icon 314. Button 2 on the interface device 14 has thus been designedto trigger the reflex sensation when pressed. This process is fast,simple, and versatile. When the user achieves a sensation exactly asdesired, the sensation can be saved as a resource file and optimizedsoftware code for use in the application program is generated. TheButton 2 selection might be provided in other ways in differentembodiments. For example, the user might select or highlight thedesigned force icons in design space 306 and then select the Button 2icon in pallet 304 to indicate that the highlighted forces will betriggered by Button 2.

FIG. 6 illustrates interface 300 where a force sensation ischaracterized in the design space 306. When an icon 308 in design space306 is selected by the user, the icon 308 expands into a force sensationwindow and graphical environment for setting and testing the physicalparameters associated with the selected sensation. For example, in FIG.6, a spring sensation type 320 has been selected from the condition list322 and provided as icon 324 in the design space 306. A spring window326 is displayed in design space 306 when icon 324 is selected. Withinspring window 326 are fields 328 characterizing the force, including theaxis 330 (and/or direction, degree of freedom, etc.) in which the forceis to be applied, the gain 332 (or magnitude) of the force, and theparameters 334 associated with the force sensation. For example, for thespring sensation, the positive stiffness (“coefficient”), negativestiffness (“coefficient”), positive saturation, negative saturation,offset, and deadband of the spring sensation are displayed asparameters. The user can input desired data into the fields 328 tocharacterize the force. For example, the user has specified that theforce is to be applied along the x-axis (in both directions, since nosingle direction is specified, has specified a gain of 100, and hasspecified saturation values of 10,000 in positive and negativedirections. The user can also preferably specify all or some of theparameters in graphical fashion by adjusting the size or shape of theenvelope, the height or frequency of the waveform, the width of thedeadband or springs, the location of a wall on an axis, etc. by using acursor or other controlled graphical object.

As the user inputs values into fields 328, the resulting additions andchanges to the force sensation are displayed in an intuitive graphicalformat in the force sensation window. For example, in the springsensation window 326, graphical representation 336 is displayed.Representation 336 includes an image 338 of the user object 34 (shown asa joystick, but which also can be shown as other types of user objects),an image 340 of ground, an image 342 of a spring on the right of thejoystick 34, and an image 344 of a spring on the left of the joystick34. Representation 336 models a single axis or degree of freedom of theinterface device.

Representation 336 represents a physical, graphical model with which theuser can visually understand the functioning of the force sensation. Theuser object image 338 is displayed preferably having a shape similar tothe actual user object of the desired interface device (a joystick inthis example). Along the displayed axis, in both directions, there arespring images 342 and 344 as defined by a positive stiffness parameter(k) and a negative stiffness parameter (k). Graphically, the largestiffness of the spring to the right (coefficient of 80) is representedas a larger spring image 342. The origin of the spring condition isshown at a center position 346, since the offset parameter 348 is zero.If the offset has a positive or negative magnitude; the origin would bedisplayed accordingly toward the left or right. The deadband region isshown graphically as the gap between the user object image 338 and thespring images 342 and 344.

In the preferred embodiment, the graphical representation further helpsthe user visualize the designed force sensation by being updated in realtime in accordance with the movement of the user object 34 of theconnected interface device 14. User object image 338 will move in adirection corresponding to the movement of user object 34 as caused bythe user. The user object is free to be moved in either the positive ornegative direction along the given axis and encounter either a positiveor negative stiffness from the spring sensation. Thus, if the userobject is freely moved to the left from origin 346, the joystick image338 is moved left in the deadband region, and when the user object 34encounters the spring resistance, the joystick image 338 is displayedcontacting the spring image 344. If there is no deadband defined, thespring images 342 and 344 are displayed as contacting the joystick image338 at the center position. The edge stop images 350 define the limitsto the degree of freedom; for example, when the user object 34 is movedto a physical limit of the interface device along an axis, the joystickimage 338 is displayed as contacting an appropriate edge stop image 350.

FIGS. 7 a-7 c illustrate graphical representation 336 as the user object34 is moved by the user. In FIG. 7 a, the user moves the user object 34and image 338 in a positive direction along an axis as shown by arrow354. No force resistance is felt by the user, since the user object isin the deadband region. This is represented by displaying joystick image338 having no contact with other objects. In FIG. 7 b, the user object34 encounters spring stiffness in the positive direction and begins tocompress the spring. As shown by the graphical representation 336, thejoystick image 338 has contacted right spring image 342 and the springimage 342 is shown slightly compressed. In FIG. 7 c, the user objectcontinues to move against the spring force, as accordingly displayed asspring 342 compression in representation 336. Once the positive springstiffness is encountered, the resistance force increases linearly withcompression of the spring (as is true of a real spring). The amount ofcompression felt by the user is correlated with the amount ofcompression shown by spring image 342. If the programmer has defined asaturation value for force opposing movement in the positive direction,the force output would cease increasing with compression once thesaturation limit in the positive direction was exceeded. The saturationcan also be shown graphically, for example by displaying the applicablespring image in a different color (such as red), or by displaying amessage or indicator on the screen.

Referring to FIG. 6, once the user has tested the input parameters andsettings, he or she may change any of the existing information or addnew information by inputting data into fields 328. Any such changes willinstantly be displayed in window 326. For example, if the user changesthe coefficient (stiffness) of the spring on the right, the spring image342 will immediately be changed in size to correlate with the new value.The user thus gains an intuitive sense of how the sensation will feel bysimply viewing the representation 336. The user can then determine howthe sensation will feel with more accuracy (fine tuning) by moving theuser object and feeling the sensation. Thus, the graphicalrepresentation 336 as displayed clearly demonstrates to the user thevarious effects of parameters on the force sensation and additionallyallows the user to experience the forces coordinated with the graphicalrepresentation.

FIG. 8 illustrates another graphical representation 360 that can bedisplayed in interface 300 for a spatial texture condition. Joystickimage 362 is moved in coordination with movement of the user object 34,as described above. A spatial texture is graphically designated in thedisplayed axis by left grating 364 and right grating 366, whichrepresent “bumps” in the texture. Left grating 364 has a different sizeof “bump” and a different spacing between bumps than right grating 366.The appropriate texture is felt by the user on user object 34 andvisualized on representation 360 as the user object is moved through thetextured region. The user preferably can specify the space betweenbumps, the size of the bumps, the magnitude of the bumps (shown by theheight of the grating in representation 360), and the overall size of atextured region in an axis. Each axis can preferably be separatelycharacterized with textures. An alternative graphical representation ofa texture condition is described with reference to FIG. 24.

FIG. 9 a illustrates a graphical representation 370 that can bedisplayed in interface 300 for a wall condition. Hard-stop images 372and/or 374 can be provided in the path of travel of the joystick image376. As shown in FIG. 9 b, when the user object is moved to encounterthe wall force, the joystick image 376 is correspondingly moved as shownby arrow 378 against the stop image 372. The user can specify thelocation of the wall, the hardness of the wall, and other parameters asdiscussed above for a wall condition. For example, if the user specifiesthe wall as having a hard like metal material, the image of the joystick376 will not tend to bend or compress the stop image 372. However, ifthe wall is specified as a flexible, rubber-like material, the joystick376 can be displayed moving into the stop image 372 or the stop imagecan be displayed as “compressing” or shrinking as the wall “flexes” inresponse to the user object moving into it.

Other condition force sensations may also be similarly graphicallyrepresented in design space 306. For example, a damping condition can bedisplayed similarly to the spring condition, where a schematicrepresentation of a damper is displayed in each direction on an axis.Another alternative damper representation is shown with respect to FIG.12. An inertia condition can be represented using a graphical image of amass on top of or connected to the joystick image 338, where the size ofthe image indicates the size of the mass. A friction condition can berepresented by a texture having bumps or the like, or by a region havinga specific color or shade.

In other embodiments, a 2 dimensional force sensation (i.e. two degreesof freedom) can be displayed in the window 326 by showing an overheadrepresentation of the user object. For example, a circular user objectimage can be displayed in the middle of two sets of spring images in across formation, each set of springs for a different degree of freedom.

FIG. 10 illustrates interface 300 with a graphical representation for aperiodic wave (effect) sensation. Periodic window 380 is displayed inresponse to the user selecting (e.g., double clicking on) periodic icon382 that has been dragged into design space 306. The periodic window 380includes a waveform source field 384, magnitude scale 386, envelopeparameters 388, direction dial 390, trigger parameters 392, and agraphical representation 392. Waveform source field 384 allows a user toselect from multiple available types of signal wave sources for theeffect. In the case of FIG. 10, the user has selected a square wavesource. Graphical representation 394 is displayed having a shape basedon the wave source chosen. Thus, a square wave is graphically displayedin the example of FIG. 10. The direction of the waveform may also beselected using dial 396 (which is partially obscured by the wave sourcedrop-down menu) and field 397. A period 399 may also be input to specifythe frequency of the waveform.

The magnitude scale 386 can be adjusted by the user to select amagnitude of the wave shown by graphical representation 394. In thepreferred embodiment, the scale is a slider control knob 398 that can bemoved by the user along the scale 400, where the scale 400 is preferablyarranged in a vertical orientation corresponding to the magnitude scaleof graphical representation 394 to permit greater ease of visualizationon the part of the user. In other embodiments, other magnitude selectionfields or objects may be provided.

Envelope parameters 388 allow the user to shape the waveform into adesired effect. For example, parameters 388 preferably include aduration field 402, a gain field 404 (where “gain” can be used as aglobal scaling factor or multiplier for force magnitudes output by theinterface device 14), and attack and fade parameters 406 to permit thespecifying of impulse magnitude and fade rate. Direction dial 390 is agraphical object allowing a user to specify the direction of the effectin two dimensions. The user may drag or otherwise specify the angle ofthe pointer, which is also shown in direction field 408 (dial 396 ispreferably similar). Trigger parameters 392 allow a user to assigntrigger button(s) to the designed effect. The repeat interval field 410allows a user to specify the amount of time before the effect isrepeated if the designated button is held down. These parameters andcharacteristics can be entered as numbers in the displayed input fieldsor prompts, or can be input by dragging the graphical representation 394of the waveform with a cursor to the desired shape or level.

The parameters, when specified, cause the graphical representation 394to change according to the parameters. Thus, if the user specifies aparticular envelope, that envelope is immediately displayed in thewindow 380. The user can thus quickly visually determine how specifiedparameters exactly affect the periodic waveform. The user can alsoactivate the waveform sensation and grasp the user object to experiencethe actual force sensation. Preferably, the graphical representation 380is animated or a pointer is moved in coordination with the output of theforce sensation on the user object. For example, if an impulse and fadeis specified, the wave is animated so that the impulse portion of thewaveform is displayed when the impulse force is output on the userobject, and the fade is displayed when the output force fades down to asteady state level. Alternatively, the entire waveform can be displayed,and a pointer or other marker can designate which portion of thewaveform is currently being output as a force on the user object. Thisfeature enables the user to realize how different portions of the waveaffect the feel sensation on the user object.

FIG. 11 illustrates interface 300 displaying a graphical representationof an advanced periodic sweep sensation. This type of waveform mayinclude additional variables and features over the standard waveformeffect described with reference to FIG. 10. A periodic sweep sensationis similar to a standard periodic waveform or vibration, but isdifferent in that the direction of the force sweeps between a start andend orientation or direction. A start dial 412 and an end dial 414 areused by the user to define the starting and ending directions for theperiodic sweep. In example of FIG. 11, the user has chosen a sine waveas the signal source in field 384. The user also has assigned values tothe magnitude, period, and of the signal, similar to the waveform ofFIG. 10. The user has also activated the envelope feature and hascreated an impulse wave shape using attack and fade parameters 406. Inaddition, the user can assign a phase using a phase pointer 416 andphase field 418, which indicate the phase angle of the waveform. Theseparameters and characteristics can be entered as numbers in an inputfield or prompt, or can be input by dragging the graphical outline ofthe waveform with a cursor to the desired shape or level. When the userwishes to test the force sensation, the user can feel the direction ofthe force sweep through the directions as specified in the dials 412 and414 and can thus easily determine the correlation of the dials and thedesired feel sensation.

Other waves that can be designed and tested in the interface 300 includea “smart pop” and a vector force. For example, a Vector force can bedesigned using a window similar to window 380, where the direction ofthe force is selected with dial 390. An envelope could also be specifiedfor the vector force, if desired, using window 390 and displayedtherein.

Dynamic force sensations, when selected in design space 306, aresimilarly displayed in a sensation window and provide parameter fieldsinto which the user may enter parameter data. A visual representationcan be displayed as the simulated physical system described above. Forexample, the Dynamic Control Law sensation has parameters that directlyaffect the components of the displayed physical system and can bereadily viewed and tested by the user. For the other dynamic sensations,the user can be shown the mapping of the parameters of the selecteddynamic sensation to the dynamic control law parameters so the user canview how the parameters effect the simulated physical system. In otherembodiments, a more appropriate representation might be displayedinstead of or in addition to the physical system described above. Forexample, for the sling and paddle sensations, a representation of theball and sling can be displayed. For Dynamic Liquid, the user object canbe displayed in the middle of animated liquid which undulates inconjunction with the movement of a simulated mass. For Dynamic Recoil, apicture of a gun or weapon can move in conjunction with the blast andreverberation of the sensation. Other animations and representations canbe provided as desired.

Once a force sensation has been designed using the graphical tools asdescribed above, the definition can be saved as a resource ofparameters. By accessing the interface resource from an applicationprogram, the resource is converted automatically from a parameter set tocode in the desired language or format, e.g., Direct-X by Microsoft®Corporation for use in the Windows™ operating system. For example, theforce feedback resource can be provided as or in a DLL (Dynamic LinkedLibrary) that is linked to an application program. In one embodiment,the DLL can provide the application program with effects defined ascompleted Direct_X Structs (DI_Struct), where the application programmercan then create effects by using the CreateEffect call within Direct-X(or equivalent calls in other languages/formats). Or, the DLL canperform the entire process and create the effect for the applicationprogram, providing the programmer with a pointer to the sensation. Oneadvantage of using the first option of having the programmer callCreateEffect is that it gives the programmer the opportunity to accessthe parameters before creating the effect so that the parameters can bemodified, if desired.

FIG. 12 illustrates interface 300 displaying a graphical representationof a damping condition (damper) in design space 306. The user hasdragged a damper icon 324 into the design space 306. A damper window 450is displayed in design space 306 when damper icon 324 is selected.Within damper window 450 are two main windows, one for each axis(assuming two axis interface device). The second axis has not beenspecified in the example of FIG. 12. Within the first axis window arefields 452 characterizing the damping force, similar to fields 328 inspring window 326 of FIG. 6. The axis or axes in which the force isapplied is selected in field 454. If both axes are selected, then awindow for each axis is displayed and includes a graphicalrepresentation of the force sensation. The user can select a globalforce gain using slider 456. A defaults button 461 can be selected bythe user to return all parameter values to default levels (preferably,the user can save preferred default levels if desired). The user canalso select both-axes box 458, which causes the parameters of one axisto be automatically mimicked for the other axis, i.e., the parameters ofone axis are copied to the parameters of the other axis. When theparameters of one axis are modified, the parameters of the other axisare automatically changed to be the same. The user can select symmetricbox 460 to make each direction on an axis mirror each other, i.e., theparameters in one direction are automatically copied to the otherdirection on that axis. If both boxes 458 and 460 are selected, the userneed only edit force sensation parameters for one direction of one axis,and the force in all the other directions of all the axes will becharacterized the same as the edited direction. Thus, boxes 458 and 460allow easy specification of symmetric forces.

The main damper window 462 offers two modes: simple and advanced. Thesimple mode is shown in FIG. 12. In this mode, a column of representedliquid 464 is shown for the negative direction on the first axis, and acolumn of represented liquid 466 is shown for the positive direction onthe first axis. The height of each liquid column indicates the magnitudeof damping in that direction, where the height is equivalent to adamping constant b in the equation F=bV, where v is the velocity of thedamped object and F is the resulting force.

When testing the feel of the damping force, the user moves the userobject, such as a joystick, and feels the force sensation in real time.In interface 300, the middle line 468 represents the position of theuser object. When the user moves the user object in the negativedirection represented in window 462, the line 468 moves to the left. Tothe user, it looks as if the line is moving against a large column ofwater or liquid, and the feel of the user object feels the same way. Asthe line moves left, the column of liquid 464 gets thinner and thecolumn of liquid 466 gets wider. In addition, liquid preferably isanimated on display screen 20 to shoot out of left pipe 470 as the usermoves the line left. This conveys the damping concept to the user in agraphical, intuitive way. A similar result occurs if the user moves theline 468 to the right, into column 466, except a smaller damping forceis felt.

As described above, the normal procedure for a force designer in usinginterface 300 is to input parameters for a selected type of forcesensation, test the way the force feels by manipulating the user object,adjusting the parameters based on the how the force feels, anditeratively repeating the steps of testing the way the force feels andadjusting the parameters until the desired force sensation ischaracterized. Normally, the user would then save the resultingparameter set describing this force sensation to a storage medium, suchas a hard disk, CDROM, non-volatile memory, PCMCIA card, tape, or otherstorage space that is accessible to a computer desired to control theforce feedback. The user also preferably assigns an identifier to thestored parameter set, such as a filename, so that this force sensationcan be later accessed. Thus, other application programs running on ahost computer can access the parameter set by this identifier and usethe designed force sensation in an application, such as in a game, in agraphical user interface, in a simulation, etc.

The icons 451 and 453 are designed to help the user with the design offorce sensations from previously stored force sensations. Clip objectsicon 451, when selected, provides the user with a list or library ofpredefined, common force sensations that the user can use as a base orstarting point, i.e., the user can modify a common spring conditionconfiguration to quickly achieve a desired force. This library can beprovided, for example, from commercial force providers or other sources.Favorites icon 453, when selected, causes a list of force sensationsthat the user himself or herself has previously stored on the storagemedium and which can also be used as a starting point in designing forcesensations.

FIG. 13 illustrates interface 300 displaying the damping condition as inFIG. 12. However, in FIG. 13, the user has adjusted the columns of waterto change the damping force, where column 464 has been decreasedslightly, and column 466 has been increased by a large amount. In thepreferred embodiment, the user can select a column using a cursor anddrag the level of the liquid column up or down to adjust the dampingforce. This, in effect, adjusts the damping coefficient b in thatdirection. The user can also adjust coefficients by directly inputtingvalues into fields 452.

FIG. 14 illustrates interface 300 displaying the damping condition ofFIG. 12. However, in FIG. 14, the user has selected the advanced modefor graphically representing a damping condition. The user has selectedbutton 472 to select advanced mode. In this mode, the columns of liquid464 and 466 of simple mode are no longer displayed. Instead, a force vs.velocity profile 474 for a damping condition is displayed in window 462.The profile 474 represents all aspects of the damping condition, much ofwhich was not represented in simple mode. For example, the saturationvalues are shown as control points 478, deadband is shown by controlpoints 480, and coefficients are shown by the slope of lines 482. Thisrepresentation is less intuitive than the simple model and wouldtypically be used for designers have some experience in designingdamping sensations. As with all the sensations, the user can move theuser object in directions on the appropriate axis, and line 484 moves asa result based on the velocity of the user object, where the user feelsthe damping sensation provided by the displayed profile at the pointwhere line 484 intersects a line 482. The displayed parameters arepreferably sent to the local microprocessor of the interface device. Thelocal microprocessor then outputs the specified force while the hostcomputer displays the graphical changes in interface 300. In alternateembodiments, the host can directly output control signals to actuatorsto control any force sensations as well.

An inertia icon shown in palette 302 (of FIG. 16, for example) can beselected to similarly design an inertia condition in a window in designspace 306. The inertia force can be graphically represented by a forceversus acceleration profile, similar to the force versus velocityprofile displayed for the advanced damping condition.

FIG. 15 illustrates the advanced damping model of FIG. 14 after the userhas adjusted some of the parameters of the damping force sensation. Inthe preferred embodiment, the user may select the control points 478 and480 and drag them to any desired position. This adjusts the saturation,offset and deadband values directly, and also adjusts the coefficientsby adjusting the slope of lines 482.

Also in FIG. 15, the user has adjusted the negative directioncoefficient to be negative, i.e. a negative slope. This type of controlis meant for advanced users, since a negative damping force is unstable:it means that the faster the user moves the user object in thatdirection, the stronger will be the damping force urging the user objectin that direction, rather than resisting the user object.

FIG. 16 illustrates interface 300 displaying an alternative graphicalrepresentation of a spring condition. FIG. 16 also shows the variety ofconditions 491 available to be selected from the condition list. Therepresentation used in FIG. 6 can be used for a spring condition aswell. In FIG. 16, the user has selected spring icon 490 in the designspace 306. A spring condition window 492 is displayed in the designspace 306 when icon 490 is selected. As in the damping condition window450 of FIG. 12, the spring window 492 includes parameters 452 forcharacterizing the spring force, as well as gain 456 and axis control454. A window is displayed for each axis in which the force is to beapplied. The greyed out window for the second axis condition indicatesthat no force is presently assigned to that axis.

In first axis window 494, a simple mode and advanced mode is available,similar to the damping condition. In FIG. 16, simple mode has beenselected by the user. Spring images 496 are displayed from each edge ofwindow 494, where spring image 496 a is for the negative direction andspring image 496 b is for the positive direction. When the user movesthe user object along the displayed axis (the x-axis), line 498 moves inthe corresponding direction. When the line 498 moves into a spring image496, the microprocessor outputs the specified spring force on the userobject so the user can feel the characterized force sensation. As theuser object continues to be moved into the spring, the spring imagecompresses as a real spring would. The empty space between spring images496 indicates the deadband region where no forces are output. It shouldbe noted that the user will feel a spring force if any component of theuser object's motion is along the x-axis; if the user moves the userobject at a 45-degree angle (where the x-axis is at 0 degrees), then acomponent of the spring force in the x-axis will be felt. This componentwill be a weaker spring force than if the user object were moveddirectly on the x-axis. This is also preferably the case for all theconditions of the interface 300. In some alternate embodiments, thespring force might be turned off in all directions except for movementprecisely (or within a tolerance) of the displayed axis.

FIG. 17 illustrates spring condition window 492 of FIG. 16 after theuser has adjusted the parameters of the spring force sensation. In thepreferred embodiment, the user may adjust the stiffness (k) of thespring force by selecting control points 500 at the edges of the frontof the spring images 496 with a cursor. The user can drag the controlpoints to adjust the widths of the spring images, which in turn adjuststhe stiffness parameter (where stiffness k is a constant in the equationF=kx, x being the displacement of the user object and F being theresulting force). A thicker spring image indicates a larger stiffnessparameter, and a stronger spring force. Thus, image 496 a is wide andindicates a large spring force in the negative direction, and theopposite in the positive direction.

The user may also move the front ends of the spring images closertogether or further apart, thus adjusting the deadband and offsetparameters. The current location of the user object is indicated by line498; the dashed line 502 indicates the center position on the displayedaxis. As parameters are adjusted, they are sent to the localmicroprocessor which then implements the newly characterized force onthe user object (if appropriate).

FIG. 18 illustrates the advanced mode for the spring condition of FIG.16. As in the damper condition of FIG. 14, the advanced spring conditionshows a force vs. displacement profile in window 494 instead of thespring images 496. All the parameters for the spring condition aregraphically represented in window 494, including saturation values asindicated by control points 504 (saturation values were not representedin the simple mode of FIG. 16). The deadband and offset are defined bycontrol points 506, while the stiffness is indicated by lines 507. Thisrepresentation is less intuitive than the simple model and wouldtypically be used for designers have some experience in designing springsensations. As with all the sensations, the user can move the userobject in directions on the appropriate axis, and line 508 moves basedon the displacement of the user object, where the user feels the springsensation provided by the displayed profile when the line 508 intersectsthe lines 507. The steepness of the slope of lines 507 provides anintuitive representation of the amount of spring stiffness provided. Thedisplayed parameters are preferably sent to the local microprocessor,which outputs the specified force on the user object while the hostcomputer displays the graphical changes in interface 300.

As with the advanced damping model, the control points 504 and 506 maybe moved by the user by selecting the desired point and dragging it to anew position. This adjusts the saturation, offset and deadband valuesdirectly, and also adjusts the stiffness by adjusting the slope of lines507. A negative stiffness can also be specified, which is not possiblein the simple mode of FIG. 16; but a negative stiffness is betterrepresented as a slope with a different image as described below withreference to FIG. 21.

FIG. 19 illustrates interface 300 displaying active windows for both x-and y-axes of the interface device. Field 454 is adjusted by the user todisplay both axes. For the first axis (x-axis), displayed in window 494,the user has selected the advanced mode as described in FIG. 18. For thesecond axis (y-axis), displayed in window 510, the user has selected thesimple mode as described in FIG. 17. When the user moves the userobject, the line 508 moves simultaneously with line 509 as long as theuser object movement has both x- and y components. If two simple modesare simulataneously displayed in windows 494 and 510, spring images inboth axes may be compressed simultaneously with the appropriate movementof the user object.

FIG. 20 illustrates interface 300 displaying the damping conditionwindow 450 of FIG. 12 simultaneously with spring condition window 492 indesign space 306. This may indicate that the user is designing acompound force sensation consisting of two different force sensations.As shown, the user has designated the x-axis of the user object to haveboth a spring force, represented by spring images 496, as well as adamping force, represented by images 464 and 466. The user can test theresulting compound force sensation by moving the user object along thex-axis. The microprocessor is sent both sets of parameters andsuperimposes one force sensation on the other. Additional forcesensations can similarly be dragged as icons into design space 306 andopened to windows by selecting the icons, thus creating a compound forcesensation with many different individual sensations.

FIG. 21 illustrates interface 300 displaying a graphical representationof a slope condition. As shown, the user has selected slope icon 520from the list of conditions displayed in sensation palette 302. The icon522 is displayed in design space 306, and after the user selects icon522, slope condition window 524 is displayed in design space 306. As inthe other condition windows, slope condition window includes parameters452, 454, and 456. A graphical representation of the slope condition isdisplayed in window 526. The user has selected simple mode in thisexample, and is only specifying a force in the first axis of theinterface device (the advanced mode for the slope condition ispreferably identical to the advanced mode of the spring condition,described above in FIGS. 18 and 19).

A slope condition is represented as a ball 528 controlled by the userand rolling on a hill 530. The ball 528 starts in the center of thehill, and as the user moves the user object to the right, the ballbegins to roll down the hill to the right. A dashed line 529 isdisplayed through the middle of the ball and moves with the ball toindicate the position of the user object. As in the real-worldequivalent, the ball moves faster the further away from the top itrolls. A corresponding force sensation is output on the user objectduring this visual representation, where the force sensation is providedas a negative spring stiffness. This is the same type of force asprovided in the spring condition, except the stiffness k is a negativevalue. The further the user moves the user object from the flat top areaof the hill, the stronger is the force pulling the user away from thetop of the hill. This is an unstable type of force, since further onemoves the user object in a direction, the greater the force in thatdirection. This type of force is well modelled by the ball on a hillrepresentation, and allows the user to intuitively picture and designforces having a negative stiffness parameter.

The user may adjust the parameters of the slope condition by draggingcontrol points provided on the hill image. Control points 532 controlthe size of the deadband and the offset, and is represented as the sizeand location of the flat top area of the hill. Control points 534control the stiffness of the slope force, which is the curvature of thebill. The location where the hill changes from a curvy slope to a linearslope (at points 534) is the saturation value, which can be adjusted bymoving control points 534.

FIG. 22 illustrates another example of a graphical representation of theslope condition. In this example, the offset is zero, so the top of thehill is centered at the center point of the axis. Both sides of the hillhave close to the same curvature, reflecting that the stiffness valuesin positive and negative directions are close to each other in value.

FIG. 23 illustrates a third example of a graphical representation of theslope condition. In this example, the user has defined a negativestiffness in the positive direction and a positive stiffness in thenegative direction. The negative stiffness is represented as a downwardslope of a hill, as in the examples of FIGS. 21 and 22. The positivestiffness is represented as an upward slope of a hill. This upward slopeis essentially a different way of representing a spring condition as inFIG. 16, which also is defined by a positive stiffness. The advantage tousing the slope representation as in FIG. 23 over the springrepresentation of FIG. 16 is that an axis can be intuitively designedwith a positive stiffness in one direction and a negative stiffness inthe other direction, which is not as easily visualized using the springgraphical representation of FIG. 16.

FIG. 24 illustrates interface 300 displaying an alternate graphicalrepresentation of a texture condition. Either the representation of FIG.24 or the representation of FIG. 8 may be used. The advantage to therepresentation in FIG. 24 is that both axes of the interface device aredisplayed in a single window or area.

In FIG. 24, the user has selected a texture condition icon 540 fromsensation palette 302. The texture icon 542 has been dragged into designspace 306 and has been selected, resulting in texture condition window544 being displayed in the design space 306. Texture condition windowincludes a style parameter 546 which is similar to the axis field 454 ofthe damper and spring condition windows, allowing the user to selectwhich axes the texture is to be provided. Gain parameter 548 is a globalscaling factor for force magnitudes to, for example, adjust force outputlevels for different hardware. Spacing parameter 550 determines thespacing between the “bumps” of the texture. Since both x-axis and y-axisare selected in window 544, the spacing parameter 550 applies to bothaxes. Different spacing can be applied to each axis by individuallyselecting an axis in field 546 specifying the spacing for that axis,selecting the other axis in field 546, and specifying the spacing inthat axis. Density parameter 552 determines the width or thickness ofthe bumps of the texture. When both axes are selected in field 546, thewidth in both axes is the same. The density for individual axes can bespecified similarly to the spacing parameter 550. The roughness slidersallow the user to specify a roughness in positive and negativedirections on the axes specified by the style parameter 546. Theroughness indicates the intensity of the texture; for cases wheretexture is simulated by intermittent damping, it is the coefficient fordamping in the bump regions.

Window 554 displays a graphical representation of the texture defined bythe parameters and allows a user to adjust the parameters graphically.The texture is displayed as a field of rectangles 555 or squares, wherethe space between the rectangles is the spacing parameter and the sizeof the rectangles shows the density. Center lines 557 divide the fieldinto four spatial quadrants, representing the workspace of the userobject. The intersection of center lines 557 indicates the currentposition of the user object. Thus, when the user moves the user objectin the two axes, the intersection moves accordingly. When theintersection moves over a rectangle 555, the microprocessor outputs abump forces in accordance with the specified parameters. When theintersection is between rectangles 555, no force is output. In analternative embodiment, the position of the user object can be indicatedby a dot, circle or other graphical object, which can move in accordancewith the user object.

Axis check boxes 560 allow the user to select which quadrants (ordirections) on the axes are provided with the specified texture. If abox 560 is checked, the corresponding quadrant on that axis is providedwith the texture; if the box is unchecked, the associated quadrant isnot provided with the texture. The graphical representation 554 isupdated accordingly. For example, if the left box 560 is unchecked, theleft half of the display in window 554 is greyed out or shown as a solidcolor, indicating a lack of texture. Note that, for example, if the userobject is positioned in the right half of display 554 and the left halfof the display has no texture, the texture force is still output whenthe user object is moved to the left as long as the user object ispositioned in the quadrant to the right of the center line 557.

If the user selects only a single axis in which to apply a texture usingstyle parameter 546, the window 554 preferably displays lines, insteadof squares, oriented perpendicularly to the selected axis, where thelines have a thickness equal to the density parameter and are spacedapart a distance equal to the spacing parameter.

The user can preferably graphical adjust the specified texture byselecting the spacing control point 562 and/or the density control point564 with a cursor and dragging the selected control point in certaindirections. For example, spacing control point 562 can be dragged to theleft to decrease the spacing on the x-axis and y-axis, and can bedragged to the right for the opposite effect on the x- and y-axes. Thedensity control point can similarly affect the density of the texture,as in field 552. Alternatively, four control points can be provided,where two of the control points control the spacing and density on oneaxis (or in one direction), and the other two of the control pointscontrol the spacing and density on the other axis (or direction).

FIG. 25 illustrates interface 300 displaying an angle spring condition.The user has selected the angle spring icon 580 from the sensationpalette 302 and has selected the icon 582 in the design space 306 tocause angle spring window 584 to be displayed. An angle spring conditionis similar to a spring condition as shown in FIG. 16, except that adirection of the spring force can be specified. In window 584, adirection dial 586 is provided to allow the user to specify a direction.The user may either select and drag the pointer 588 of the dialgraphically to select an angle, or input an angle directly in field 590.Preferably, an angle spring always is defined in terms of 2 axes (ormore), since the angle is defined within two degrees of freedom.

Window 594 displays the graphical representation of the angle spring.The axis (degree of freedom) represented in window 594 is the axis alongthe specified angle. The user moves the user object and dashed line 592moves within spring window 594, similar to the embodiment of FIG. 16.Only the component of motion of the user object in the specifieddirection is displayed as line 592 moving. The full spring forceindicated graphically by springs 596 will only be output on the userobject if the user moves the user object in the direction specified bydial 588 and field 590. If the user moves the user object in otherdirections, only a component of the full force will be felt by the user,i.e., if the user moves along the x-axis (0 degrees) and a 30 degreespring force is specified, the user will feel a weaker spring force thanif moving along the 30-degree direction.

Preferably, the other angle forces shown in palette 302, such as anglebarrier 592, angle slope 594, and angle wall 596, have directionspecification and output similar to the angle spring described above.

Other conditions are also listed in palette 302. The wall is a conditionthat provides an obstruction force to the movement of the user object,as discussed above with respect to FIGS. 9 a and 9 b. The location ofthe wall in provided axes in represented graphically by a large shadedline or block on an axis into which the user object is obstructed frompenetrating. A barrier is similar to a wall, except the user object canpenetrate the barrier and pop through to the other side of the barrier,and thus includes a thickness parameter which can be displayedgraphically as a thickness of a block. The “spring at current” and“slope at current” conditions provide forces that are initiated at acurrent position of the user object; thus, a spring at current forcewill have an origin centered at the current location of the user object.This is useful for designing condition forces centered at otherpositions of the user object other that its origin position.

FIG. 26 illustrates interface 300 displaying another embodiment of agraphical representation of a wave or effect periodic force sensation.The user has selected a periodic effect icon 600 in palette 302, and hasselected the icon 602 in design space 306 to display the periodic window604. Periodic window 604 is similar to the periodic graphicalrepresentations of FIGS. 10 and 11, described above. In window 604, theuser is allowed to select the duration of the periodic wave usingsliders 606, and may also select an infinite duration with box 608. Thegain and offset may be selected using sliders 610, and other parametersare provided in fields 612. A graphical representation of the periodicwaveform is shown in window 614. The parameters in fields 612 can begraphically adjusted by the user by dragging control points 616 of thewaveform, as described with reference to FIG. 11. A frequency of thewaveform can be adjusted by dragging a displayed wave to widen or narrowthe displayed oscillations of the wave. Trigger buttons for the periodicwave can be determined in fields 618, and the direction of the periodicwave in the user object workspace is determined using dial 620 and field622.

To test the specified periodic wave, the user preferably selects startbutton 624, which instructs the microprocessor to output the specifiedforce sensation over time to the user object so the user can feel it. Inthe preferred embodiment, a graphical marker, such as a vertical line orpointer, scrolls across the display window 614 from left to rightindicating the present portion or point on the waveform currently beingoutput. Since graphical display is handed by the host computer and forcewave generation is (in one embodiment) handled by a localmicroprocessor, the host display of the marker needs to be synchronizedwith the microprocessor force generation at the start of the forceoutput. The user can stop the output of the periodic sensation byselecting the stop button 626.

While this invention has been described in terms of several preferredembodiments, it is contemplated that alterations, permutations andequivalents thereof will become apparent to those skilled in the artupon a reading of the specification and study of the drawings. Forexample, many different parameters can be associated with dynamicsensations, conditions, and effects to allow ease of specifying aparticular force sensation. These parameters can be presented in thegraphical interface of the present invention. Many types of differentvisual metaphors can be displayed in the interface tool of the presentinvention to allow a programmer to easily visualize changes to a forcesensation and to enhance the characterization of the force sensation.Furthermore, certain terminology has been used for the purposes ofdescriptive clarity, and not to limit the present invention. It istherefore intended that the following appended claims include all suchalterations, permutations, and equivalents as fall within the truespirit and scope of the present invention.

1. A method for implementing a force sensation design interface, saidmethod comprising: displaying said force sensation design interface on adisplay device of a host computer; receiving input from a user to saidforce sensation design interface, said input selecting a type of forcesensation to be commanded by said host computer and output by a forcefeedback interface device, said force feedback interface deviceincluding a user manipulatable object graspable by a user and moveablein a degree of freedom; receiving input from a user defining physicalcharacteristics of said selected force sensation; displaying a graphicalrepresentation of said selected force sensation as characterized by saiduser, wherein said graphical representation provides said user with avisual demonstration of a feel of said characterized force sensation;and commanding said characterized force sensation to said force feedbackinterface device coupled to said host computer such that actuators ofsaid force feedback interface device output said force sensation on saiduser object in conjunction with said visual demonstration of said feelof said characterized force sensation. receiving additional changes tosaid characterized force sensation from said user after said forcesensation is output and displaying said additional changes in saidgraphical representation, wherein a force sensation modified inaccordance with said additional changes is output by said actuators onsaid user object.